Temperature compensated accelerating pump



Oct. 31, 1967 E. SCALA, JR 3,356,071

TEMPERATURE COMPENSATED ACCELERATING PUMP Filed NOV. 18, 1964 3 Sheets-Sheet 1 EUGENE L. SCALA JR.

lNl ENTOR A T TO/PNE rs Oct. 31, 1967 SCALA, JR 3,350,071

TEMPERATURE COMPENSATED ACCELERATING BUMP Filed NOV. 18, 1964 3 Sheets-Sheet 2 EUGENE L. SCALA JR.

INVENTOR By M a.

ATTORNEYS United States Patent 3,350,071 TEMPERATURE COMPENSATED ACCEL- ERATING PUMP Eugene L. Scala, Jr., Southfield, Mich., assignor to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed Nov. 18,1964, Ser. No. 412,177 7 Claims. (Cl. 261-34) ABSTRACT OF THE DISCLOSURE connected to the valve in the accelerator pump discharge conduit.

This invention relates to a temperature compensated accelerating pump for the charge forming device of an internal combustion engine.

The function of an accelerating pump, to inject a small amount of liquid fuel into the induction passage of a charge forming device during rapid opening of its throttle valve, is well known. It is equally well known that the required amount of fuel discharge of an accelerating pump is considerably less at high temperatures than at low temperatures. For this reason, it has been proposed to vary the output of an accelerating pump either seasonally through a mechanical adjustment or automatically in response to temperature variations. The automatic mechanisms heretofore provided have required some form of temperature responsive element for their operation.

It has been common practice to provide a separate temperature responsive element that acts only upon the accelerating pump.

It is an object of this invention to provide a temperature compensated accelerating pump that does not necessitate the provision of a separate, thermally responsive element.

Charge forming devices incorporating a first embodiment of this invention includean induction passage and a throttle valve for controlling the flow of mixture through the induction passage. 'Fuel discharge means are provided to discharge fuel into the induction anterior to the throttle valve. A choke valve is provided in the induction pas sage anterior to the fuel discharge means for controlling the flow of air through the induction passage. Accelerating pump means having a pump member operatively connected to the throttle valve deliver a metered charge of fuel to the induction passage upon a predetermined degree of opening of the throttle valve. Means including linkage means are provided to operatively connect the choke valve to accelerating pump means for regulating the amount of fuel discharged by the accelerating pump means in a given degree of opening of the throttle valve in response to changes in the position of the choke valve.

In a further embodiment of this invention, automatic means including a temperature responsive element may be provided for positioning the choke valve. The automatic means also will control the amount of discharge of the accelerating pump means through a linkage system.

'The temperature compensated accelerating pump mechanisms heretofore proposed for the most part have embodied some form of structure for altering the stroke of the accelerating pump mechanism. A more accurate and more positive control may be provided through the use of a metering valve in the accelerating pump discharge circuit. In an embodiment of this invention, a metering valve provided in the accelerating pump discharge circuit may be operatively connected to the choke valve so that it is positioned in accordance with variations in the position of the choke valve.

Further objects and advantages of this invention will become more apparent as this description proceeds, .particularly when considered in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a top plan view of a portion of a charge forming device of an internal combustion engine embodying this invention.

FIGURE 2 is a cross sectional line 2 2 of FIGURE 1.

FIGURE 3 is a cross sectional view, in part similar to FIGURE 2, showing another embodiment of this invention.

Referring now in detail to the drawings and in particular to the embodiment shown in FIGURES l and 2, a charge forming device for an internal combustion engine is indicated generally by the reference numeral 11. The charge forming device 11 includes a body portion 12 and a cover plate 13 that is aflixed to the body member by a plurality of screws 14. The cover plate 13 has a raised air horn section 15 that forms an air inlet passage 16 that is in communication with one or more induction passages formed in the body portion 12. The body portion induction passages are shown partially in FIGURE 2 and are identified by the reference numeral 17. A fuel bowl 18 is formed in the body portion 12. A float 19 and float valve assembly (not shown) is provided to maintain a uniform head of fuel in the fuel bowl 18. Fuel is discharged from the fuel bowl 18 into the induction passages 17 by any suitable f-uel discharge means. A throttle valve (not shown) may be provided at the lower end of the induction passages 17 posterior to the discharge end of the fuel discharge means for controlling the rate of mixture discharge from the charge forming device 11.

A choke valve 21 is supported for rotation about an axis that extends transversely to the air inlet passage 16 by a choke valve shaft 22. The choke valve shaft 22 is journaled at its opposite ends in the cover plate 13. An automatic choke actuating mechanism, indicated generally by the reference numeral 23 and embodying a temperature responsive element (not shown), may be suitably connected to the choke valve shaft 22 to position the choke valve 21 in response to temperature variations. The specific automatic choke actuating mechanism employed does not form a part of this invention.

An accelerating pump mechanism, indicated generally by the reference numeral 2.4, is provided to discharge a metered quantity of fuel into the induction passages 17 between the throttle valve andthe choke valve 21 during opening of the throttle valve. The accelerating pump mechanism 24 comprises an annular pumping cavity 25 that is formed within a cylindrical projection 26 that. extends from view taken along the one side of the carburetorbody portion 12. A flexible diaphragm 27 is positioned across the mouth of the pumping cavity 25 and is held in place by an accelerating pump cover 28 that is afiixed to the cylindrical projection 26 by a plurality of bolts 29. The diaphragm 27 is clamped between a pair of rigid discs 31 and 32 that are aflixed, in turn, to an accelerating pump plunger 33. The pump plunger 33 is guided for reciprocation in a bore 34 formed within the accelerating 'pump cover 28. An accelerating pump drive linkage including a pump operating lever 35 is provided to transmit motion from the throttle valve to the accelerating pump plunger 33 and diaphragm 27.

The diaphragm 27 and accelerating pump plunger 33 are normally urged in an outward direction by a coil spring 37 that engages the disc 31 and a cylindrical boss 38 that extends coaxially within the pumping cavity 25. When the throttle valves are moved to an open position, the accelerating pump drive linkage, including the pump operating lever 35, urges the accelerating pump plunger 33 and diaphragm 27 inwardly to decrease the volume of the pumping cavity 25.

During the outward movement of the diaphragm 27, fuel may be drawn into the pumping cavity 25 through a horizontal passage 39 that extends from the lower end of the fuel bowl 18 and an intersecting, vertical passage 41 that is formed within the cylindrical boss 38. A ball check valve 42 is provided within the passage 41 so that fuel may flow into the pumping cavity 25 through the passages 39 and 41 but cannot return to the fuel bowl 18 from the pumping cavity 25.

During opening of the throttle valve, the diaphragm 27 is deflected inwardly to impel fuel from the pumping cavity 25 through a horizontal passage 43 that extends through the body portion 12 below the fuel bowl 18. The passage 43 is intersected by a vertical passage 44 that terminates at the lower end of a vertical passage 45 that is formed adjacent to the induction passages 17. A cap screw 46 is threaded into a tapped hole 47 formed in the body portion 12 at the upper end of the passage 45. The cap screw 46 is formed with a vertically extending passage 48 that extends completely therethrough. A ball check valve 49 is positioned within the passage 45 and a weighted rod 51 is positioned within the passage 48 of the cap screw 46 to provide a flow restriction to the discharge of the accelerating pump mechanism 24.

An accelerating pump discharge nozzle assembly 52 is affixed to the body portion 12 by the cap screw 46. A pair of pump shooters 53 positioned within the nozzle assembly 52 are directed downwardly to discharge into the induction passages 17. The upper ends of the pump shooters 53 register with an annular recess 54 that is formed around the cap screw 46. The recess 54 is intersected by a horizontal passage 55 so that fuel flowing past the rod 51 may be discharged from the pump shooters 53.

A metering rod 56 is supported in the upper end of the passage 48 formed in the cap screw 46. The metering rod 56 is adapted to move into the intersection of the passages 48 and 55 to offer a further restriction to the flow of fuel to the pump shooters 53 and thus act as a metering valve. The upper end of the metering rod 56 is notched, as at 57, for receipt within a forked end 58 of a leaf spring 59. The other end of the leaf spring 59 is formed with an aperture through which an air cleaner hold-down stud 61 passes. The air cleaner hold-down stud 61 is affixed within a tapped hole 62 formed within the carburetor body portion 12. A cinch nut 63 is positioned at the upper end of the air cleaner hold-down stud 6 1 to aflix the leaf spring 59 relative to the cover plate 13.

The choke valve 21 is fromed with an upsturned cam portion 64 that is adapted to engage the leaf spring 59 and deflect it upwardly when the choke valve 21 is in its closed or choked position as shown in the solid line view in FIGURE 2. When the leaf spring 59 is deflected upwardly, the metering rod 56 will be raised so that it will not interfere with the free flow of fuel from the accelerating pump mechanism 24 out of the pump shooters 53. When the engine is warm and the choke valve 21 is moved to its open or unchoked position by the automatic ohoke actuating mechanism 23, the cam portion 64 will permit the leaf spring 59 to deflect downwardly to the dotted line position shown in FIGURE 2. In this position, the lower end of the metering rod 56 will obstruct the communication between the passages 48 and 55 to restrict the amount of fuel discharged into the induction passage by the accelerating pump mechanism 24 for a given degree of opening of the throttle valve. The desired relationship between the position of the choke valve 21 and the meter rod 56 may be selected by appropriately forming the cam portion 64.

In the previously described embodiment, the metering valve that controlled the discharge of the accelerating pump mechanism was responsive to the position of the choke valve. If the choke valve is operated by an automatic choke mechanism that is responsive to engine temperature, the rate of discharge of the accelerating pump also will be responsive to engine temperature. In some instances, it may be desirable to regulate the rate of pump discharge in response to the temperature of the intake air flowing through the air horn induction passage 16. The embodiment shown in FIGURE 3 provides this result.

In the embodiment shown in FIGURE 3, the construction of the carburetor in general, the accelerating pump and the accelerating pump metering rod are the same as that shown in FIGURES 1 and 2. The common parts have been identified by the same reference numerals and will not be described again.

In place of the leaf spring in the previous embodiment, a bimetallic leaf spring 81 is clamped between the cinch nut 63 and the carburetor cover plate 13. The outer end of the bimetallic leaf spring 81 is forked to receive the notched area of the metering rod 56. The choke valve 21 is provided with a slot 82 so that the choke valve 21 may move between its open and closed positions without contacting the bimetallic leaf spring 81.

When the temperature of the bimetallic leaf spring 81 is cold, indicating a low temperature of intake air, the outer end of the leaf spring 81 will deflect upwardly to the solid line position shown in FIGURE 3. In this position, the metering rod 56 will permit substantially unrestricted fuel flow between the passages 48 and 55 so that a full charge of fuel may be discharged from the accelerating pump 24 through the pump shooters 53. As the temperature of the intake air increases, the bimetallic leaf spring 81 will deflect downwardly to the dotted line position so that the metering rod 56 will restrict the flow of fuel from the accelerating pump 24 through the pump shooters 53.

It is to be understood that this invention is not limited to the exact constructions shown and described, but that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.

I claim:

1. A charge forming device for an internal combustion engine comprising an induction passage, a throttle valve controlling the flow of mixture through said induction passage, fuel discharge means for discharging fuel into said induction passage anterior to said throttle valve, a choke valve in said induction passage anterior to said fuel discharge means for controlling the flow of air through said induction passage, accelerating pump means having a pump member operatively connected to said throttle valve for delivering a metered charge of fuel to said induction passage upon a predetermined degree of opening of said throttle valve, and means including linkage means operatively contacted by cam means on said choke valve for regulating the amount of fuel discharged by said accelerating pump means in a given degree of opening of said throttle valve in response to the position of said choke valve.

2. A charge forming device for an internal combustion engine comprising an induction passage, 2. throttle valve controlling the flow of mixture through said induction passage, fuel discharge means for discharging fuel into said induction passage anterior to said throttle valve, a choke valve in said induction passage anterior to said fuel discharge means for controlling the flow of air through said induction passage, automatic choke positioning means operatively connected to said choke valve for positioning said choke valve in response to temperature variations, accelerating pump means having a pump member operatively connected to said throttle valve for delivering a metered charge of fuel to said induction passage upon a predetermined degree of opening of said throttle valve, and means including linkage means operatively contacted by cam means on said choke valve for regulating the amount of fuel discharged by said accelerating pump means in a given degree of opening of said throttle valve in response to the position of said choke valve.

3. A charge forming device for an internal combustion engine comprising an induction passage, a throttle valve controlling the flow of mixture through said induction passage, fuel discharge means for discharging fuel into said induction passage anterior to said throttle valve, a choke valve in said induction passage anterior to said fuel discharge means for controlling the flow of air through said induction passage, accelerating pump means having a pump member operatively connected to said throttle valve for delivering a metered charge of fuel to said induction passage upon a predetermined degree of opening of said throttle valve, a metering valve in the discharge circuit of said accelerating pump means for regulating the amount of fuel discharge by said accelerating pump means in a given degree of opening of said throttle valve, and means including linkage means operatively contacted by cam means on said choke Valve to adjust said metering valve in response to changes in the position of said choke valve.

4. A charge forming device for an internal combustion engine comprising an induction passage, a throttle valve controlling the flow of mixture through said induction passage, fuel discharge means for discharging fuel into said induction passage anterior to said throttle valve, automatic choke positioning means operatively connected to said choke valve for positioning said choke valve in response to temperature variations, accelerating pump means having a pump member operatively connected to said throttle valve for delivering a metered charge of fuel to said induction passage upon a predetermined degree of opening of said throttle valve, a metering valve in the discharge circuit of said accelerating pump means for regulating the amount of fuel discharged by said accelerating pump means in the predetermined degree of opening of said throttle valve, and means including linkage means contacted by cam means on said choke valve and connected to said metering valve for adjusting said metering valve in response to changes in the position of said choke valve.

5. A charge forming device for an internal combustion engine comprising an induction passage, a throttle valve controlling the flow of mixture through said induction passage, fuel discharge means for discharging fuel into said induction passage anterior to said throttle valve for controlling the flow of air through said induction passage, accelerating pump means having a pump member operatively connected to said throttle valve, an accelerating pump discharge circuit extending from said accelerating pump means to said induction passage for delivering a metered charge of fuel to said induction passage upon a predetermined degree of opening of said throttle valve, said accelerating pump discharge circuit including a first passage intersected adjacent one of its ends by a second passage, a metering rod supported for reciprocation within said first passage at said one end, said metering rod being movable between a first position wherein flow between said passages is restricted to a second position wherein flow between said passages is substantially unrestricted, and means operatively connecting said meter ing rod to said choke valve for moving said metering rod from its first position to its second position in response to movement of said choke valve from its open to its closed position.

6. A charge forming device for an internal combustion engine comprising an induction passage, a throttle valve controlling the flow of mixture through said induction passage, fuel discharge means for discharging fuel into said induction passage anterior to said throttle valve, a choke valve in said induction passage anterior to said fuel discharge means for controlling the flow of air through said induction passage, automatic choke positioning means operatively connected to said choke valve for positioning said choke valve in response to temperature variations, accelerating pump means having a pump member operatively connected to said throttle valve, an accelerating pump discharge circuit extending from said accelerating pump means to said induction passage for delivering a metered charge of fuel to said induction passage upon a predetermined degree of opening of said throttle valve, said accelerating pump discharge circuit including a first passage intersected adjacent one of its ends by a second passage at said one end, a metering rod movable from a first position wherein flow between said passages is restricted to a second position wherein flow between said passages is substantially unrestricted, and means operativelyconnecting said metering rod to said choke valve for movement of said metering rod from its first to its second position upon movement of said choke valve by said automatic choke positioning means from its opened to its closed position.

7. A charge forming device for an internal combustion engine comprising an induction passage, a throttle valve controlling the fiow of mixture through said induction passage, fuel discharging means for discharging fuel into said induction passage anterior to said throttle valve, a choke valve supported in said induction passage for movement about a pivotal axis that extends transverse to the longitudinal axis of said induction passage for movement from an opened to a closed position, accelerating pump means having a pump member operatively connected to said throttle valve for delivering a metered charge of fuel to said induction passage upon a predetermined degree of opening of said throttle valve, a spring member affixed at one of its ends to said charge forming device at one side of said induction passage, said spring member extending in a direction normal to the pivot axis of said choke valve, cam means formed on said choke valve, said cam means being in contact with said spring member for deflecting said spring member upon movement of said choke valve between its opened and its closed position, and means operatively connecting said spring member to said accelerating pump means for regulating the amount of fuel discharged by said accelerating pump means in a given degree of opening said throttle valve in response to the position of said choke valve.

References Cited UNITED STATES PATENTS 1,933,389 10/1933 Prentiss 261-34 1,935,351 11/1933 Chandler 261-34 1,697,423 7/ 1934 Prentiss 26134 2,899,950 8/ 1959 Dermond 261-34 3,008,697 11/ 1961 Dermond 26134 3,251,585 5/1966 Derengowski 26134 3,269,711 8/ 1966 Baldwin 261-34 HARRY B. THORNTON, Primary Examiner. TIM R. MILES, Examiner. 

1. A CHARGE FORMING DEVICE FOR AN INTERNAL COMBUSTION ENGINE COMPRISING AN INDUCTION PASSAGE, A THROTTLE VALVE CONTROLLING THE FLOW OF MIXTURE THROUGH SAID INDUCTION PASSAGE, FUEL DISCHARGE MEANS FOR DISCHARGING FUEL INTO SAID INDUCTION PASSAGE ANTERIOR TO SAID THROTTLE VALVE, A CHOKE VALVE IN SAID INDUCTION PASSAGE ANTERIOR TO SAID FUEL DISCHARGE MEANS FOR CONTROLLING THE FLOW OF AIR THROUGH SAID INDUCTION PASSAGE, ACCELERATING PUMP MEANS HAVING A PUMP MEMBER OPERTIVELY CONNECTED TO SAID THROTTLE VALVE FOR DELIVERING A METERED CHARGE OF FUEL TO SAID INDUCTION PASSAGE UPON A PREDETERMINED DEGREE OF OPENING OF SAID THROTTLE VALVE, AND MEANS INCLUDING LINKAGE MEANS OPERATIVELY CONTACTED BY CAM MEANS ON SAID CHOKE VALVE FOR REGULATING THE AMOUNT OF FUEL DISCHARGED BY SAID ACCELERATING PUMP MEANS IN A GIVEN DEGREE OF OPENING OF SAID THROTTLE VALVE IN RESPONSE TO THE POSITION OF SAID CHOKE VALVE. 